Related Experiment Video
Updated: Jul 11, 2026

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Evolution of a Bose-Einstein condensate in a rapidly expanding circular box
Stavros Theodorakis1, Yiannis Constantinou
1Physics Department, University of Cyprus, P.O. Box 20537, Nicosia 1678, Cyprus. stavrost@ucy.ac.cy
Abstract:
We examine the evolution of the ground state of a Bose-Einstein condensate in a two-dimensional circular box, the wall of which is initially at rest and then recedes with large and constant speed. The final state of the condensate depends on the rapidity of the expansion of the box. If the number of atoms in the condensate is small compared to the dimensionless speed of the wall, then the condensate becomes a mixture of excitations and follows the expansion of the box, leaving empty though an increasingly larger region between the condensate boundary and the wall. If, on the other hand, the number of atoms is large compared to the dimensionless speed of the wall, then the condensate is always in the ground state and spreads uniformly in all of the expanding box, the condensate boundary always coinciding with the receding wall. Approximate analytic expressions are found for the evolving wave function.
Related Concept Videos
Standing Waves in a Cavity
The Bohr Model
Equilibrium Conditions for a Particle
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
Kinetic Theory of an Ideal Gas
The number of molecules in one mole is called Avogadro's number...
Phase Transitions: Vaporization and Condensation
First Law: Particles in One-dimensional Equilibrium

